instead of
Code:
%money_ [ $+ [ $nick ] ]
use
Code:
%money_ $+ [ $+ [ $nick ] ]
or (when setting)
Code:
$+(%,money_,$nick)

If you use the last method (which is my preferred method), to get the value, you have to double evaluate the variable, thus you would use
Code:
$($+(%,money_,$nick),2)
or
Code:
$eval($+(%,money_,$nick),2)


6.02 is such an old version, that it sounds like your script was taking advantage of a bug, which has been fixed in the mean time.